Process of preparing alloy steel for die blocks and other purposes



Patented Feb. 28, 1928.

v UNITED STATES GILMORE N. HERMAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO ALLOY STEEL CORPORA- TION, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLHTOIS.

PROCESS OI? PREPARING ALLOY STEEL FOR DIE BLOCKS AND OTHER PURPOSES.

'30 Drawing.

My invention has to do with the produc tion of steel suitable for use in making die blocks and other articles for which steel having similar characteristicszis necessary or peculiarly suitable, and it has for its object to provide an alloy steel which besides having the necessary strength, durability and toughness, will possess the-requisite hardness, but will not be too hard to be machined, or to be trimmed down for resinking after it has been used to such an extent that resink-v ing is necessary or desirable; also to provide such a material that will be peculiarly homogeneous and of especially refined grain, as well as comparatively .free from surface and internal imperfections; and which will be well adapted to be used for the purposes stated without being subjected to the usual or any treatment for hardening.

Heretofore alloyv steels used for the purposes mentioned have generally been cast in the form of ingots which, after being cast,-

have been allowed to cool under atmospheric a then wit In spite of this su sequent annealing, allalways be removed and 'cer- 'tain losses from rejections due to warping stresses cannot and cracking may occur. v

In the process of hardening, as described, the surface of the steel becomes harder than the interior so that when after use the die block is trimmed down, as for resinking, a

different grain structureis exposed and die blocks which have been hardened usually have to' be annealed and rehardened after each trimming. Therefore, such hardening pr'ocesshas a tendency to produce a metal which is inferior for die block purposes. In

the makin of die-blocks, a chrome-molybdenum-nicke steel has been used containing a. relatively" small proportion of nickel, gen'-,

.erally not excee two per cent,because according to the heretofore known methods of treating such steels any greater proportion Application filed May 27, 19.26. sum No. 112,154.

of nickel would make the alloy diflicult to machine, and ive'it a tendency to warp and crack as a resu t of such hardening treatment as was re uired to bring the material to a state suita le for die block use. I have however discovered that a su erior material for that purpose may be pro uced by combining. nickel in larger proportions with chromium and molybdenum to form a steel alloy, and

then subjecting such alloy to a process of 65 treatment which, without undergoing a hardenlng process, brings it'to finished form for use in the manufacture of die blocks, and leaves it with a .peculiarlly homogeneous,

and especially refined grain, free from surface and internal imperfections, and of such degree of hardness that while it is long lived when usedas a die block, it is not too hard be machined, or trimmed down .for resink mg, and, therefore, may be successfully used 76 after numerous resinking operations. The fact that the material is peculiarly homogeneous and of especially refined grain throughout, and is free from surface and internal imperfections and strains, is an important 80 consideration; these qualities adapt the die block for resinking, as thereis little danger that in that operation a different grain structure, or cracks or fissures will be encoun tered, which would, of course, prevent 8! further use of the block.

In the production of the improved product above referred to I may make use of a an alloy steel having substantially the fol-7' lowing composition:

Percent. Carb n Y a I 0. to 0. 801 Manganese.. 0.20to 1. 00. Silicon 0. 10 to 0. 80 Chromium 0. to 2. 25 95 Molybdenum 0. 20 to 1. 50

Nickel, above 1.00. per cent.

The percentage of the several elements above indicated give the permissible ranges of variation in the production of a material 100 v for various purposes, but I have found the following analysis to be .that best suited for die block manufacture: v

. Per cent Carbom- 0. to 0. 105 Manganese "0. to 0. Silicon; 0. 10 to O. 25 Chromium 0.75 toO. Molybdenum 0. 30 to 0. 50

Nickel no. 2.-7 5to3.25 11o ferently treated in several of the stages leading to the production of the finished material, and, therefore, the resulting product has not had the novel characteristics which distinguish my improved product from that heretofore derived from such alloy steel.

According to my improved method a heat, having the chemical analysis above indicated, is made, preferably in an electric furnace, and the finished heat is poured into ingot molds. The steel is then allowed to stand until it becomes thoroughly solidified.

. The ingot is then stripped, and, preferably without being allowed to cool below. a surface temperature of approximately 1000 F.,

it is charged into a heating furnace to be reheated to a proper forging temperature.

If forging cannot take place immediately after casting the ingot, provision is made so that such further cooling as occurs shallbe very slow and at the same time uniform, to avoid setting up strains.

By subsequent slow and uniform heating the ingot is brought up substantially above its critical temperature, preferably to 2000- F. to 2100 F. After reaching the proper forging temperature the ingot is put under a forge press for forging it into die blocks and-during the forging process is not allowed to cool below the point where it loses the requisite plasticity. After the die blocks .are finished to size in the forging operation,-while still hot they are transferred to a preheated soaking pit or furnace having a tem erature of approximately- 1000 F. The b ocks at that time have a temperature of about 1400 F. In this way all the die blocks'areequalized in the soaking pit or furnace to a temperature of about 1000 F., and then additional heat is applied to the furnace and by slow and .uniform heating the die blocks are brought upto. a temperature of about1700, F. and held at such temperature until they become equalized in temperature throughout, after which the heat is shut offend the blocks are allowed to cool slowly and uniformly down to a-temperature where they will not be afiected by. at-

' mospheric conditions. They are then removed from the furnace to allow them to come to atmospheric temperature; The annealing process to which the die blocks are subjected in the soaking pit or furnace as above described completes the treatment of the material so that after the usual machin- 1,eeo,79o

ing and sinking operations the die" blocks are ready for use; I thus eliminate the steps of hardening and tempering that have heretofore been necessary, which not only-saves time and expense, but also avoids losses that are apt to occur incidentallyto such heat treatment, such." as those due to warping, shrinking orcra'cking.

The die blocks produced by the method described are peculiarly homogeneous and of especially refined'grain throughout, and are practically free from surface and internal imperfections, so that there is very little loss on that account. They are of such a degree of toughness and hardness .that by actual tests they have been found to be greatly superior to other chrome-molybdenum-nickel I alloy steel die blocks, which usually require hardening b heat treatment? The factthatl because of their homogeneity and uniform hardness my improved die blocks may, be

trimmed for resinking, gives them. an added feature of superiority.

While as I have stated, in practicing my improved process I, refer toflc'onduct the several steps as hereiiihefore specifically described, some latitude is permissible. This mode of treatment, that is to say, the keeping. of the ingot and forgings' hot, or otherwise avoiding the setting up of strains therein, as decribed, during the intermediate stages of the process antecedent to the annealing operation, may also be applied with advantage to chrome-molybdenum-nickel alloy steels the analysis of which varies considerably from the' preferred percentages hereinbefore mentioned, since, by appropriately varying the relative percentages of the principal elements, a sufficiently hard material can be produced, without hardening by heat treatment, to be suitable for the making of die blocks and analogous articles.

The range of analysis of the various elements as hereinbefore given, which are included in my invention, is necessarily a wide one, since the interrelation of the several elements is such that-the increase of one usually means the decrease of another; for instance with a higher chrome or nickel content a lower carbon content would follow. Also my invention includes the substitution in whole or in part for any of the elements mentioned, of any equivalent thereto, such as vanadium, tungsten, cobalt, and others; .The claims hereinafter made are therefore intended to include the sub stitution of equivalents for the elements specifically mentioned therein.

It should be understood that while my improved process is peculiarly suitable for the manufacture of die .blocks, it may also beused for making trimmer die steels, in-.

sert die steels,

cles which can e made toadvantage from steel having similar characteristics.

piston rods, and other arti-"- I iso- What I claim as new and desire to secure by Letters Patent, is N 1. The method of'treating alloy steel analyzing chromium .25-225' per cent, molybdenum .20-1.50 per cent, and nickel above 1.00 per cent, to form a finished material for the purposes specified requiring no hardening and subsequent tempering which con- I sane, and then annealin sists in molding the steel into an ingot,

heating the ingot tofatemperature of from 1800 F. to 2300 F. while substantially free from internal strains, and forging the the forgmg.

2. The method of treatmgalloy steel analyzii1g chromium .25-225 per cent, molyber cent, and nickel above.

denum .201.50 1.00 per cent, to orm a finished material for the purposes specifiedrequiring no hardening and subsequent tempering which consists in molding the steel 'into an ingot,

1 heating the in ot to a temperature of from a temperature of from 1400 F. to 1700 -.F.,.

vdenum .20-L per cent, and nickel above 1.00 per cent, to form a finished material for the purposes specified requiring no harden.- ing and subsequent tempering which consists in molding the steel into an ingot, al-

lowing the ingot to solidify, heatingit to a temperature of from 1800 F. to 2300 F.

without allowing it to cool below a surfacetemperature of approximately 1000"- F.,.

forging: the in ct intodie blocks, and-then annealing the orgings by heating them to a temperature of from 1400 F. to 1700 F., and subsequently allowing them to cool slowly and uniformly.

' 4. he method 'of treating alloy steel analyzingchromium .75-.95 er cent, molybdenum .30-.50 per cent, an nickel 2.75-3.25

per cent, to form a finished material for the purposes specified requiring no hardening and subsequent tempering which conslsts' in molding the steel into an ingot, heating the ingot to a temperature of-from 1800 1". to 2300 F. while substantially freefrom internal strains, and for ing the same, and

then annealing the forging.

5. The method of treating alloy steel. en

alyzing chromium '.75.95 er cent, molybdenum .30-.50 per cent, an nickel 2.7 5-3.25

'per. cent, to form a finished material for the purposes; specified requirin'g nohardening K and subs uent tempering which consists-in molding t e steel into an ingot, heating the ingot to a temperature of'frorn 1800 F. to.

2300-F. without permitting it tocool ma-.

terially *after solidification, and forging-the same, and then annealing the forging by slow and uniform heating up to a temperature of from 1400 F. to 1700' F., followed by slow anduniform cooling.

6. The method of treating alloy steel anealyzing chromium '.75.95 per cent, molybdenum .30-.50, per cent, and nickel 2.7 5-3.25 per cent, to form a finished material for the purposes specified requiring no hardening.

and subseqpent tempering which consists-in molding t e steel into an ingot, allowing the ingottosolidify, heating it to a temperature of from 1800 F. to 2300 F. without allowing it to cool below a surface tempera]- ture of approximately 1000 F., forging the ingot into die blocks, (and then annealing the forgings by heating them to a temperature of from 1400 F. to 1700 F., and sub uentl allowing them to 0001 slowly fan unlform y. 

